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Weber 38 Vacum Connections?


GreenSwede

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So, I bought a Weber 38/38 DGMS and have started fiddling with getting it on. I just noticed there are two vacuum connections, I´m not entirely sure which to use for the dizzy advance.

 

I did search, both here and google, but found no good pics matching my carb..

 

Ideas? I´m guessing the one on the side, below the choke mechanism, cause that looks the most like the one I used on the 32/36. But if so I have no idea what the other one is for?

 

Very grateful for any light shed upon the matter!

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Looking well. I think the vac on the other side can be blocked up

Might be to connect to the air breather flap like on an e21.

Just wonderimg what Jetting your using?

 

WIll do that. I think it´s right. I´ll probably notice if I get the vaccum for the dizzy on the wrong side of the throttle plates..

 

Haven´t driven it yet. Nearly there. I thought I´d do it right and align the throttle rod with the shaft in the Weber (as they say), which turned out to take some time - new hole for the rod, had to fabricate a new bushing and holder for the new bushing and so on. Seems like it will work fine now.

 

Bought it from Top End, jetted as follows by them. (on stock engine with 4-1 headers)

 

 

50 IDLE
135 MAINS
185 AIRS 
PUMP JET 55
E-TUBES F50
 
Hopefully there´ll be a test drive tomorrow, cause I´m curious.
But, I´m installing a wideband sensor this winter, to get it just right come spring.
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You will want the ported vacuum or the one above the throttle plate.  An easy method to see where the ports are getting the vacuum signal from is to take a can of carb cleaner, insert the straw in to each port, look inside the bore to see where the cleaner comes out when you squirt the cleaner.  The reason you do not want the manifold vacuum is because at idle (high vacuum) your advance mech will be fully advanced and as you open (No/low vacuum) the throttle the signal is lost and your ignition is retarded, just when you need the advance.

Earl

74 02Lux

02 M Roadster 

72 Volvo 1800ES

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Yes, I know. I actually tried that once when reinstalling the 32/36 after I had rebuilt the engine. I had an empty port on the manifold, didn´t think and plugged it there. Easy to try, if idle raises when you plug it in, it´s wrong.

But I´ll try that! To see where the actually signal is from. Maybe there is one good for idle mixture setting..

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The diagram below shows the port below the throttle plates as where to attach for my 73

http://www.dagsites.com/emissions/73_2002p.JPG

Ported vacuum, not manifold vacuum I would think? Or the factory would have hooked right to the manifold.

I have a 38 38 to put in as well, only an IE sourced one, with elec choke.

What is the final word on this?

 

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The diagram below shows the port below the throttle plates as where to attach for my 73

http://www.dagsites.com/emissions/73_2002p.JPG

Ported vacuum, not manifold vacuum I would think? Or the factory would have hooked right to the manifold.

I have a 38 38 to put in as well, only an IE sourced one, with elec choke.

What is the final word on this?

 

But if it´s below the throttle plates, it is the same as manifold, right..?

 

I hooked up the dizzy to the one on the right picture, passenger side of carb. And plugged the one behind the sprockets.

The car ran nicely, but I actually forgot to remove the hose and see how it affected the idle while running. Will do to make sure.

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